Drywall is a type of board made from plaster, wood pulp, or other material, used especially to form the interior walls of houses. Joint compound (also known as drywall compound or mud) is a white powder of primarily gypsum dust mixed with water to form a mud the consistency of cake frosting. The terms “drywall compound”, “joint compound” and “compound” will be used interchangeably throughout this application. Joint compound is used with paper or fiber joint tape to seal joints between sheets of drywall to create a seamless base for paint on interior walls.
In operation, when joint compound is used to seal joints between sheets of drywall, the compound must be sanded to create a smooth texture before painting. If the area joined by the joint compound is not sanded, then such area will appear rough, unfinished and look unprofessional. Therefore, the area joined by fiber joint tape and joint compound is sanded before painting.
WO 2007035338 discloses a roll of fiberglass mesh drywall tape that is sandable. However, a major problem with drywall tape taught in WO 200735338 is that it is difficult to know how much sanding is required and when to stop sanding because in many cases the color of the compound applied onto the sandable portion is the same color of the sandable coating after the compound is dry. Because the sandable coating is the same color of the compound, operators cannot differentiate between the sandable coating of the compound versus the sandable portion of the tape. In operation, if too much compound is sanded off the tape disclosed in WO 200735338, then the fibers of the fiberglass tape will be exposed. If the fibers are exposed those fibers would appear after painting of the wall, which is unsightly, and therefore would require a person to re-compound, re-sand and re-paint a wall.
Having to re-tape, re-compound, re-tape and re-paint is very time consuming, and inefficient. Re-compounding alone would take several hours because a person after applying compound for a second time would have to wait several hours for the compound to dry before re-sanding the compound. This is not only time consuming, but it also increases labor costs and material costs.
As a result, there exists a need for improvements over the prior art and more particularly for a more efficient way of preventing oversanding of surfaces.